Power harvesting devices are used to generate power from energy embodied in a structure with which the device is associated. Thermal, solar, wind, chemical or kinetic energy may be harvested for generating power. Kinetic energy may be in the form of structural vibrations. Power harvesting devices are commonly used in wireless sensor networks.
The efficiency of power generation from kinetic energy in the form of structural vibrations is dependent on the correlation between the resonant frequency of the harvesting device sensor element and the resonant frequencies of the structural vibrations. The closer the resonant frequency of the harvesting sensor is to that of a significant frequency of the vibrations, the greater the power that can be harvested.
One problem with harvesting energy from structural vibrations is that the frequencies of the vibrations in a given structure commonly vary depending on the operational loads or conditions to which the structure is subjected. Furthermore, in some operational states, the amplitude of any vibrations in a structure may be so low that little power can be harvested from them.